1. Field of the Invention
The present invention relates to a cooling system for a variety of electronic packages that are used in electronic equipment such as electronic computers, workstations, personal computers and the like.
2. Description of the Related Technology
As is well known, electronic equipment such as electronic computers, workstations, personal computers and the like are equipped with circuit boards on which are mounted a variety of electronic packages such as CPUs (central processing units) as represented by MPUs (microprocessor units) and MCMs (multi-chip modules). In recent years, the electronic packages are becoming more dense and, hence, generate more heat when they are in operation. It need not be pointed out that in order to guarantee proper operation of the electronic packages and to extend their life, it is necessary to suitably cool the electronic packages to maintain their temperatures to lie within predetermined ranges.
In order to cool the above-mentioned highly sophisticated electronic packages, it has heretofore been proposed to use, for example, a heat sink 10 with a cooling fan as shown in FIGS. 15(a), 15(b) and 15(c). The heat sink 10 with cooling fan comprises a heat sink plate 12, a small electric motor 14 mounted on the center of the heat sink plate 12, and a fan 16 attached to an output shaft of the small electric motor 14. Furthermore, a number of heat-radiating fins 18 are extending from the heat sink plate 12 and are nearly radially arranged so as to surround the fan 16. As will be obvious from FIGS. 15b and 15c, the heat sink 10 with cooling fan is directly attached to a highly dense electronic package 20. Upon driving the small electric motor 14, therefore, the highly sophisticated electronic package is efficiently cooled. That is, upon rotating the fan 16, an air flow is produced among the heat-radiating fins 18 as indicated by arrows in FIGS. 15(a) and 15(b), whereby the heat conducted to the heat-radiating fins 18 from the highly dense electronic package 20 through the heat sink plate 12 is efficiently radiated.
FIG. 16 illustrates another conventional cooling system in which a heat conducting plate element 24 is attached onto the highly dense electronic package 20 that is mounted on a circuit board 22. A pair of heat pipes 26 extend from the heat conducting plate element 24, and many heat-radiating fins 28 are attached to the ends of the pair of heat pipes 26. According to the prior art, the heat is efficiently conducted from the heat conducting plate element 24 to the heat-radiating fins 28 through the heat pipes 26, and the highly dense electronic package 20 is favorably cooled.
It has been pointed out that the conventional cooling system shown in FIGS. 15(a), 15(b) and 15(c) has a problem in that the heat sink with cooling fan is itself bulky. For example, the junction temperature of a highly dense electronic package (MPU: microprocessor unit) having a square shape of a side of about 4 cm that generates 15 watts of heat can be lowered to be not higher than 85xc2x0 C. at an ambient temperature of 40xc2x0 C. When the heat is generated in further increased amounts, however, the heat sink with cooling fan of a larger size must be employed to guarantee the operation of the MPU maintaining a temperature of 85xc2x0 C. In the vicinities of a place where the highly dense electronic package is mounted, however, no space is available for installing such a large heat sink with cooling fan. In order to cope with an increased amount of heat without using the heat sink of a large size, it can be contrived to employ a liquid cooling system requiring, however, conduits and coolant feeding device resulting in a considerable increase in the cost for cooling.
The conventional cooling system of the type shown in FIG. 16 has a problem in that a forced air cooling is necessary to assist the radiation of large amounts of heat from the heat-radiating fins and that the cooling fan must be provided separately from the cooling system. When the housing of an electronic equipment is provided with a cooling fan for forced air cooling, the place for installation must be determined in relation to a place where the heat-radiating fins are formed, imposing a limitation on the freedom for designing the electronic equipment as a whole. There also arise problems in that there is no freedom in the combination of the cooling fan and the heat-radiating fins, it is not easy to improve the conduction of heat through the fins, and the heat-radiating fins themselves must be formed in a large size. So far, no particular attention has been given to space for laying out the heat pipes and heat-radiating fins in the housing.
The object of the present invention is therefore to provide a system which is capable of efficiently cooling a variety of electronic packages and, particularly, highly sophisticated electronic packages that are used in the electronic equipment without greatly limiting the freedom for designing the electronic equipment as a whole.
According to the present invention, a cooling system comprises at least one independent heat radiator-holding portion formed in advance in a housing of an electronic equipment, a heat radiator installed in said heat radiator-holding portion, a heat conducting plate element provided for at least one electronic package in said housing so as to receive heat therefrom, and a heat conducting passage element (e.g., a heat pipe) which is connected at its one end to said heat conducting plate element and is connected at its other end to said heat radiator so that heat is conducted from the heat conducting plate element to said heat radiator.
It is desired that the heat radiator includes a number of heat-radiating fins provided at the other end of the heat conducting passage element. It is further desired that the heat radiator has a cooling fan for cooling said number of heat-radiating fins.
The heat radiator comprises a second heat conducting plate element connected to the other end of said heat conducting passage element (e.g., a heat pipe), heat-radiating pin elements extending from both sides of said second heat conducting plate element, and cooling fans provided on both sides of said second heat conducting plate element. Otherwise, the heat radiator comprises the second heat conducting plate element connected to the other end of said heat conducting passage element, and a cold plate secured to the second heat conducting plate element.
It is desired that the heat conducting passage element is at least partly formed as a bellows.
According to another aspect of the present invention, there is provided a cooling system for electronic packages, comprising a plurality of independent heat radiator-holding portions formed in advance along the outer circumference of a housing of an electronic equipment, a plurality of heat radiators installed in said heat radiator-holding portions, a heat conducting plate element provided for at least one electronic package in said housing so as to receive heat therefrom, and a plurality of heat conducting passage elements (e.g., heat pipes) which are connected at their ends on one side thereof to said heat conducting plate element and are connected at their ends on the other side thereof to said heat radiators so that heat is conducted from the heat conducting plate element to said plurality of heat radiators.
The first heat conducting plate element provided for the electronic package is connected to a relay heat conducting plate element through a second heat conducting passage element, and the heat conducting passage elements extending from the first heat conducting plate element and from said relay heat conducting element are connected to the heat radiators. Otherwise, the first heat conducting plate element provided for the electronic package is connected to a relay heat conducting block element through the second heat conducting passage element, and the heat conducting passage elements extending from the first heat conducting plate element and the relay heat conducting block element are connected to the heat radiators.
According to a further aspect of the present invention, there is provided a cooling system for electronic packages comprising at least one independent heat radiator-holding portion formed in advance in a housing of an electronic equipment, a heat radiator installed in said heat radiator-holding portion, a plurality of heat conducting plate elements provided for a plurality of electronic packages arranged in said housing so as to receive heat therefrom, a plurality of first heat conducting passage elements which are connected at their ends on one side thereof to said heat conducting plate elements and are connected at their ends on the other side thereof to said heat radiator so that heat is conducted from said plurality of heat conducting plate elements to said heat radiator, and second heat conducting passage elements for connecting said plurality of heat-conducting plate elements to each other.
According to the present invention, as will be obvious from the above-mentioned constitution, the heat radiator is installed in at least one independent holding place formed in advance in the housing of the electronic equipment and, hence, the heat-radiating capacity of the heat radiator can be freely selected depending upon the holding place.